We propose to study the structure and organization of human globin genes from normal individuals and those with genetic disorders in globin gene expression (thalassemias) using recombinant DNA procedures. A gene isolation technique which involves screening libraries of human DNA with gene-specific hybridization probes will be used to isolate and characterize each of the members of the globin gene family from normal DNA. Characterization of the cloned DNA may indicate the presence, location and size of noncoding intervening sequences in the globin genes, and may reveal similarities within and surrounding genes that are coordinately and/or sequentially expressed during development. In addition, this information will be used for comparison to the corresponding sequences in the DNA from individuals with various forms of thalassemia. Sequence differences may identify recognition sequences for proteins involved in transcriptional initiation or termination, or RNA splicing, processing or translation. The analysis of naturally occurring mutations in globin gene expression will be complemented by studies which involve the alteration of specific cloned DNA sequences in vitro (site directed mutagenesis), followed by an analysis of the behavior of the altered DNA in vitro, or in vivo using cell-free transcription or translation systems or eukaryotic host-vector systems to introduce cloned globin genes into cells in which they are ordinarily expressed.